What he does is only getting the location information and simply cross-referencing it with Google Street View / Google Maps Data. That being said: It's an art installation http://bengrosser.com/projects/tracing-you/ to provoke questions about privacy in a more closely connected world than ever. Noble idea.
"First it looks up the IP address using ipinfo to obtain geolocation. This is represented as a latitude/longitude pair (e.g. 48.8631831,2.3629368) that identifies a precise location on the earth. The latitude/longitude is sent to Google, where it queries the Street View, Static Maps, and Javascript Maps data services."
Not too impressive though.
I can imagine a non-technical relative/friend of mine seeing such an installation, then telling me that you can track down every internet user accurately and even show the building he is living in and me having to explain why that is not the case and a ridiculous notion.
No matter how noble the cause, deception is wrong. After all, I don't tell my kids their heads may explode if they take illegal drugs...
"... Sometimes what this image shows is eerily accurate; other times it is wildly dislocated. ... How accurate are the system’s data sources and when might they improve?"
And more from the artist's page about the project:
"... How close it gets is very much dependent on how networks are built, configured, operated, and distributed where you are, which network you use, and the accuracy of the data associated with those networks."
Pasting this into the javascript console of a browser (just tested in Chrome and Safari):
navigator.geolocation.getCurrentPosition(function(pos){console.log(pos)})
Then feeding the latitude and longitude into Streetview it gives me (after granting location permission) the front door of the building next door.
Note that if you can come up with a convincing explanation for why an unsuspecting user should click the location request popup, this'll defeat the VPN as a means of hiding your location... "Click here and allow location access to see hot girls ready to meet in your area!"
Read later that it updates with each visitor...
My best guess would be using a geoIP to detect the user's city and then using Google Map's street view from that city and showcase it for a couple of seconds. The webmaster would have more accurate data if he had asked for HTML5 geo location permission.
